[The cytological picture in pleural pneumocystosis].

We report a case of a HIV+ patient treated with prophylactic aerosolized pentamidine. The patient showed evidence of tensive right pneumothorax and slight pleural effusion. The pleural fluid was aspired from the drainage and processed in our laboratory. The cytologic examination of aspired fluid revealed abundant Pneumocystis carinii organisms. The cytologic presentation is peculiar in pleural fluid because of the presence of a large amount of trophozoites and a small number of cysts. Direct examination and Giemsa stain are suitable methods to detect trophozoites. The diagnosis can be confirmed by Gomori and Toloidine Blu stains that demonstrate the presence of isolated and scarce cysts. Pneumocystis carinii can also be recognized in Papanicolaou-stained smears as eosinophilic aggregates.